Voluntary measures, such as vessel slowdowns, can be an effective way of managing concerns posed by shipping-related underwater noise radiation to at-risk whales according to a report released earlier this year.

The Enhancing Cetacean Habitat and Observation (ECHO) program, a research and management initiative led by the Vancouver Fraser Port Authority, recently reported that reducing vessel speeds is an effective way of reducing underwater noise. This may in turn benefit the behaviour and foraging success of southern resident killer whales (SRKW).

A summer 2017 research trial led by the ECHO program analyzed underwater noise associated with 577 piloted commercial vessel transits implementing a voluntary slowdown (out of a total of 951 piloted transits during that time) through Haro Strait. Researchers used a hydrophone located in waters just off Lime Kiln State park on San Juan Island, WA to measure the underwater noise in the area, which is used by SRKWs.

The ECHO program report stated that once small and recreational boat noise along with other noise, such as high wind and current, is filtered out, the median reduction is 2.5 dB, “which is approximately equivalent to a 44 per cent reduction in sound intensity.” Reduced vessel speeds and strong vessel participation rates could reduce the affected foraging time for SRKWs by 11.5 per cent for an average vessel traffic day and 10.3 per cent for a high-traffic day compared with baseline conditions, the report said.

“The results of the vessel slowdown trial indicated that voluntary measures can be an effective way of managing threats to at-risk whales. Reducing vessel speeds is an effective way of reducing the underwater noise generated at the vessel source, as well as reducing total underwater noise in nearby habitats, which may in turn benefit the behaviour and foraging success of SRKW,” the report stated. The 2017 slowdown added between 21 and 41 minutes to the transit time through Haro Strait, depending on the vessel type.

Underwater noise reduction initiatives and research resumed in 2018, concluding October 31. For 2018, the Haro Strait voluntary vessel slowdown initiative used different vessel speeds and a dynamic slowdown start and end date in an effort to both maximize vessel participation and benefit to the whales, when they were present. Prior to the start of this voluntary initiative almost 70 marine transportation organizations confirmed their intent to support or participate it.

Participation in a separate Strait of Juan de Fuca lateral displacement trial, led by the ECHO program and Transport Canada, was also strong with almost 60 Canadian and US marine transportation organizations supporting or participating. The lateral displacement trial was a voluntary trial to study how laterally displacing vessels away from known SRKW feeding areas affects the underwater noise levels in those foraging areas.

The cumulative participation rate for deep sea vessels was 88 per cent over 15 slowdown weeks for the 2018 Haro Strait voluntary vessel slowdown and for a related project, the Strait of Juan de Fuca lateral displacement trial, 57 per cent over nine weeks.

The 2017 and 2018 voluntary vessel slowdown actions were designed and implemented through collaboration with a Vessel Operators Committee and a variety of stakeholders including the Chamber of Shipping, Shipping Federation of Canada, Cruise Lines International Association – North West and Canada, Council of Marine Carriers and their respective members, the Pacific Pilotage Authority and BC Coast Pilots, Washington State Ferries, Canadian federal government agencies and scientists.

The ECHO program has a long-term goal of developing voluntary mitigation measures that will lead to a quantifiable reduction in threats posed by vessel traffic and port activities to at-risk whales in the region. The ECHO program has structured its research and initiatives to address three threat categories: acoustic disturbance, physical disturbance and environmental contaminants.

Trans Mountain has provided $1.6 million to the ECHO program to support its research and mitigation development initiatives. Trans Mountain is not involved in program development or governance, but the Project has committed to incorporate best practices and appropriate mitigations into the Trans Mountain vessel acceptance standard and its marine terminal operations guide. For more information about the ECHO program and its research, visit the ECHO program web page here.